1. Technical Field
The present invention relates generally to handwriting recording devices for real-time digitization of handwritten text and, more particularly, to system and methods for selecting keywords in a handwriting recording device.
2. Description of Related Art
There are a variety of handwriting recording devices which digitize and electronically capture handwritten text in real-time as the text is written. Typically, these conventional handwriting recording devices utilize a digitizing tablet in conjunction with an electronic stylus (i.e., pen) to record handwriting data. The digitizing tablet generates positional data representing the coordinates of the electronic stylus by detecting, for example, RF (radio frequency) signal emissions generated by the stylus as a user applies the stylus to the surface of the tablet (e.g., when the user is writing on or near the surface of the tablet).
One type of handwriting recording device is a personal digital notepad (PDN) device. The PDN device includes an electronic stylus having an inking tip which allows the user to write on a piece of paper placed over the digitizing tablet while recording handwriting strokes (positional data). The stylus typically includes a pressure sensor which generates a "pen down" signal when the stylus is in contact with the surface of the digitizing tablet. This signal is usually conveyed to the digitizing tablet via a dedicated line or through a secondary RF emission. Accordingly, by monitoring the pen down signal and the path of the radio emission of the stylus as it move across the radio sensitive grid, the digitizing tablet may generate a data stream representing the pen strokes which comprise written text on, or in proximity to, the surface of the digitizing tablet. The term "stroke" used herein refers to a group of handwriting data which is recorded between a "pen-down" signal and a "pen-up" signal.
One embodiment of a PDN device is disclosed in U.S. patent application Ser. No. 08/747,735 entitled: "Methods, Systems and Products Pertaining To A Digitizer For Use In Paper Based Record Making Systems" filed on Nov. 12, 1996, the disclosure of which is incorporated herein by reference. One currently available embodiment of this PDN device is marketed by the A. T. Cross Company and sold under the name CROSSPAD.TM.. The CROSSPAD allows a user to record handwritten information on a standard paper notepad and simultaneously record an electronic carbon copy of the writing.
One novel feature of the CROSSPAD is its ability to record user defined keywords while a user is writing on the device. A keyword can be one word or a group of words which are selected by the user when producing a handwritten record to represent key concepts or ideas for a given handwritten paragraph or page. In particular, a keyword comprises one or more recorded strokes which correspond to the handwritten text selected by the user and are electronically tagged as a single unit. The strokes comprising the keyword are subsequently converted into a text representation of the ink using handwritten recognition technology.
Specifically, the CROSSPAD is currently configured to define a keyword in the following manner. After the user is done writing on the writing medium associated with the PDN, the user actuates a designated switch, button or menu option on the PDN to invoke a "keyword mode." While in the keyword mode, the user selects a keyword by drawing "bounding strokes" around the handwritten strokes comprising the desired keyword. The bounding strokes may take the form of a circle, a box, or any other shape drawn by the user to delineate an area encompassing the desired (keyword) handwriting strokes. For instance, as shown in FIG. 1, a bounding stroke "b" (in the shape of an ellipse) is drawn around the handwritten word "jumps" on page P. As further illustrated in FIG. 1, the bounding stroke "b" is processed by the PDN to detect the extremities of the bounding stroke "b", i.e., the maximum X and Y coordinates (i.e., Xmax and Ymax) and the minimum X and Y coordinates (i.e., Xmin and Ymin) to generate a "bounding box" (denoted as "B") through which the detected coordinates extend. All recorded strokes having coordinates which fall within the "bounding box" area are used to define the keyword.
There are various disadvantages to the current keyword selection algorithm. For instance, the user may not fully encircle a handwritten stroke. Consequently, it is possible that some or even all of the handwritten strokes that the user desires to select as a keyword will not be included in the keyword. In addition, even if the bounding stroke "b" encloses the desired handwritten strokes, the current algorithm for generating the bounding box "B" (area) may cause the keyword members to include recorded strokes that are outside the actual bounding stroke "b" (i.e., in the areas denoted as "a" in FIG. 1) made by the user. These problems can result in user inconvenience and reduce the usability of the PDN with respect to keyword selection.